Structural modular interconnectable subsoil drainage cell

ABSTRACT

A structural module comprises a rigid cell including two substantially parallel planar members, each of which defines an ordered array of circular apertures with a series of columns disposed substantially normally to the two parallel surfaces retaining the two members in a fixed spaced relationship from each other. Male interlocking means which are integral with the module project from two adjacent side edges of the module. Female interlocking means are defined the other two adjacent side edges. The modules can be secured together in side edge to side edge relation, in which relationship the male locking means from a first module engage in a female locking means of a second module. The circular shape of the perimeter of the male locking member matches the size and shape of the apertures so that one module may also be inter-engaged with a second module with each male locking member of the one module projecting into one of the apertures of the second module in an interference type fit, with the first module oriented generally normally to the second module.

FIELD OF THE INVENTION

[0001] This invention relates to an interconnectable structural module,particularly, but not exclusively, for use as a drainage module.

BACKGROUND OF THE INVENTION

[0002] The control and flow of surface water, such as rain water orstorm water, is important in preventing the build up of surface wateradjacent foundations of buildings or other structures, and in otherareas such as on playing fields, golf courses, landscaped decks, gardensand the like. In densely built up areas, the increased surface run-offof storm and rain water has resulted in massive storm water channelsbeing built to cope with the quantities of run-off water. However, theseimpervious drainage systems take up large areas of land and are not onlyan eyesore, but are expensive to build and maintain. Further, they areoften polluted by sedimentation and organic rubbish. Storm waterchannels often smell offensive and can turn into major breeding groundsfor pests and diseases.

[0003] One solution to this problem, has resulted in the invention ofsubsoil modular drainage systems such as the “NORDRAIN”™ subsoil modulardrainage system (trade mark of Nortec Geo-Systems (S) Pte Limited ofScottsu Road. #05-05 Singapore). The NORDRAIN system comprises a rigidcell including a first and a second substantially parallel planarmember, each of which defines an ordered array of circular apertureswith a series of columns which are disposed substantially normally tothe two parallel surfaces retaining the two members in a fixed spacedrelationship from each other. The circular apertures in the first andsecond planar members are out of register such that the centre of anaperture in the first member is generally opposed to a solid area of thesecond member disposed between four adjacent circular apertures in thesecond member.

[0004] Such sub-soil modular drainage systems create a permanent voidbetween a building structure and the soil profile and thus allow easypassage of excess subterranean waters to designated outlets. They arealso used in drainage applications for playing fields, golf courses andthe like and for making underground storage tanks when they areassembled in a box structure and covered in geotextile.

[0005]FIG. 1 of the attached drawings illustrates the use of a NORDRAINsub soil modular drainage system 3 against a retaining wall 1 to providerelief from hydrostatic pressure on that wall by channelling excesswaters to an appropriate outlet. A waterproof membrane 2 is disposedbetween one face of the NORDRAIN module and the wall 1, and the otherface of the NORDRAIN module is covered in a geotextile 4.

[0006] Such modules tend to be made to a particular, relatively small,size typically about 340 long×340 wide×30 mm deep and the modules arejoined together to create larger drainage structures. Although theNORDRAIN and other similar subsoil modular drainage systems work well,sometimes problems arise in assembling the modules into an appropriatelysized composite module sized for a particular application. This is oftendone using separate clips. Problems arise in particular where themodules are being used against a retaining wall in a generally verticalorientation.

[0007] It is an object of the present invention to provide an improveddrainage module with improved means for assembling the drainage modulestogether.

SUMMARY OF THE INVENTION

[0008] According to the present invention, there is provided astructural module comprising:

[0009] a first and a second substantially parallel generally planarmember retained in a fixed spaced relationship from each other by aplurality of spacers extending between the first and second planarmembers, the module having side edges extending between perimeters ofthe first and second planar members and wherein each planar memberdefines an ordered array of apertures;

[0010] male interlocking means which are integral with the moduleprojecting from at least a first one of the side edges;

[0011] female interlocking means defined in at least a second of theside edges adapted to receive a male interlocking means so that twomodules can be secured together in side edge to side edge relation;

[0012] characterised in that the size and configuration of the malelocking means relative to the size and configuration of the apertures,is such that a first module may also be inter-engaged with a secondmodule, with the first module oriented generally normally to the secondmodule with a side edge of the first module abutting a planar member ofthe second module and with each male locking member defined along saidside edge of the first member extending into one of the aperturesdefined in one of the planar members in a close or interference type fitwith the aperture.

[0013] In a preferred embodiment, the female locking means compriseelongate slots defined between the ends of two walls, forming part ofthe side edges. The slots have an open end and a closed end. The malelocking means may comprise two arms which are generally L shaped incross section. When two modules are butt joined and interlocked in endto end relation the ends of the arms engage, behind the walls definingthe slots.

[0014] The apertures are preferably generally circular.

[0015] It is preferred that the area of the apertures comprises at least50% of the surface area of the first and second planar members.

[0016] It is preferred that the apertures in the planar members arearranged substantially regularly and uniformly.

[0017] In one particularly preferred embodiment, the male locking meansequidistantly spaced along a first two adjacent sides of the module; thearrangement of male locking means along each adjacent side is asymmetric(i.e. offset). A series of gaps are disposed between each pair of malelocking means. The female locking means are also equidistantly andasymmetrically spaced along the other two sides of the module. A seriesof gaps are also disposed between each pair of female locking means. Thegaps are wider than the male members. The arrangement of male lockingmeans, female locking means and gaps is such that when a module isabutted end to end with another module, with the tops of both modulesfacing up (or both facing down) the modules will interlock. In thisarrangement the modules are butt joined and also interlocked. However,if one of the modules is turned around through 180° so that the sideshaving male interlocking means face each other, or if one of the modulesis turned upside down relative to the other because of the asymmetry ofthe arrangement of the male locking means, the male locking means simplylocate in some of the gaps and do not interlock the modules together. Inthis arrangement the modules are butt joined but not interlocked.Modules may also be butted and not interlocked by positioning together,sides having female interlocking means. The invention has the advantageover existing products in that it is not necessary to carefully alignmodules or clip them together.

[0018] In addition to use as a drainage cell, other possible uses forthe module include, a drainage layer, a protection layer, a core forcovered/uncovered panels, and when assembled as a box structure, asretention/detention tanks, table supports and the like. In addition, themodules may be used as channels/ducts for the flow of liquids, gases,solids having a small particle size, as a protection layer, as aseparator, a panel for table tops, or as panels for doors or roompartitions, exhibition stands, supports for other structures, or thelike. Other uses which benefit from the modules manner of interlocking,fluid permeation characteristics and/or shear, compression and torsionalstrengths may be envisaged.

[0019] The module may be injection moulded in PP (polypropylene) HDPE(high density polyethylene) or LPDE (low density polyethylene). However,any other suitable materials which can be moulded or cast, may be used,including aluminum and rubber.

[0020] In a related aspect, to the present invention also encompassesthe use of the nodule of the present invention, to make drainage pipingor underground tanks by assembling and interlocking the modules intoboxes or pipes and covering them with geotextile or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A specific embodiment of the present invention will now bedescribed, by of example only, and with reference to the accompanyingdrawings ill which:

[0022]FIG. 1 is a schematic view illustrating one use of a prior artdrainage modules;

[0023]FIG. 2 is a perspective view from above and the front of adrainage module embodying the present invention;

[0024]FIG. 2a is an enlarged view of a male engagement means of thedrainage module;

[0025]FIG. 3 is a top plan view of the module of FIG. 2;

[0026]FIG. 4 is a bottom plan view of the module of FIG. 2;

[0027]FIG. 5 is a front view of the module of FIG. 2;

[0028]FIG. 5a is an enlarged view of a male engagement means of themodule;

[0029]FIG. 6 is a rear view of the module of FIG. 2;

[0030]FIG. 7 is a left side view of the module of FIG. 2;

[0031]FIG. 8 is a right side view of the module of FIG. 2; and

[0032]FIG. 9 illustrates interlocking on two modules at 90° to eachother.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0033] Referring to the drawings. FIG. 2 shows a perspective view of adrainage module 10 embodying the present invention other views of whichare shown in FIGS. 3 to 8. As shown in the Figures, the drainage moduleincludes two planar members, an upper member 12 defining an upper faceor top T of the module and a lower member 14 defining a lower face orbottom B. A regular and ordered array of circular apertures 16 aredefined in both members. The size and spacing of the apertures is suchthat approximately 58% of the area of each of the planar members 12, 14is open. The arrangement of the apertures on both of the planar members12, 14 is substantially identical. However, as is best seen in FIGS. 3and 4, the apertures in the upper member 12 are out of register withthose in the lower member 14. A plurality of spacer elements 18 extendbetween the layers 12, 14 maintaining the layers in spaced apartparallel relationship. Four spacer elements 18 are located on theperiphery of each circular aperture 16, spaced 90° apart.

[0034] The forming of the modules with the apertures out of register,enables the entire structure to be injection moulded in one piece andalso improves the load bearing capabilities of the module. Typically,the horizontal compressive strength of the modules is such that theywill support a minimum weight of 150 tonnes per square metre. It ispreferred that the module is injection moulded in polypropylene or inhigh or low density polyethylene. However, other suitable materials maybe used. The usual embodiment is 250 mm wide×500 nm long as illustrated,and 30 mm deep, although modules might be made in other sizes.

[0035] As seen in FIGS. 2 and 3, male engagement means 22 also referredto as locking means, are provided along the ends or side edge areas 26,28 of two adjacent sides of the module.

[0036] As is best seen in FIGS. 2a and 5 a, each of the male engagementmeans includes two arms 36 which extend outwardly from the side wall ina direction perpendicular to the end wall before bending generallyparallel to the end wall so that in plan view (see FIG. 3) each of thearms is generally L shaped. A cross member 38 extends between the twoarms of each male engagement means. This cross member assists inpreventing the two arms from flexing or twisting.

[0037] As can be seen in FIGS. 2 and 3, the male engagement means areequidistantly spaced along the sides 26, 28 of the module. The maleengagement means are separated by a series of gaps or spaces 24 in thesides. There are seven gaps between each pair of male engagement means.The gaps are wider than the widest part of the male member.

[0038] Also, as is best seen in FIG. 3, the male engagement means areasymmetrically disposed on the sides 26, 28. The reason for this isexplained below with reference to the female engagement means 29.

[0039] The female engagement means 29 which are best seen in FIGS. 4 and6 comprise slots having one open end 30 and one closed end 32. Each slothas an shoulder or wall portion 34 extending along its edge.

[0040] With reference to FIG. 4, it can be seen that the femaleengagement means are also asymmetrically arranged on adjacent sides 34,36 of the module opposite sides 26, 28 respectively. In between thefemale engagement means, there are seven spaces or gaps 24.

[0041] Projections 50 are provided along one bottom edge of the endwall; these help to prevent movement/play between adjacent modules whenthey are inter-engaged.

[0042] When viewed front on, the upper and lower surfaces of the maleengagement means are rounded so that the front profile of the maleengagement means fits within an imaginary circle 40 as illustrated inFIG. 5a. The circle 40 is approximately the same size as the apertures16, preferably very slightly larger so as to provide an interferencepush fit with the aperture.

[0043] In contrast with existing prior art modules, the described moduleembodying the present invention, has three distinct modes ofinterfitting with other modules.

[0044] First, when it is desired to interlock two modules 10 in end toend relationship, two modules are located male side face 26 (or 28) tofemale side face 34 (or 36). The slots of the female engagement meansare positioned above the male engagement means and slid down over them.The end portions of the arms of the male engagement means slot behindthe shoulders of the female engagement means to engage and lock the twomodules together. In this arrangement the modules are butt joined andinterlocked.

[0045] However, if one of the two modules is turned around through 180°or is flipped over through 180°, the male engagement means abut a gap26, not a female engagement means (due to the asymmetry of the locationof the male and female engagement means on the sides of the module).Then the modules can simply be pushed together. The male engagementmeans simply locate in a gap 26. In this arrangement the modules arebutt joined but not interlocked.

[0046] Also, the modules can be engaged at 90° to each other asillustrated in FIG. 9 with the male engagement means, forming aninterference fit in the cylindrical apertures 16 thereby retaining themembers together. In this arrangement, the projections 50 should faceaway from the retaining wall to bias the vertically oriented moduleagainst the wall. When installing a drainage module against a retainingwall, such as is illustrated in FIG. 1, the vertically oriented module 3can thus be simply interlocked with the horizontal module on which itrests.

[0047] Also, the modules of the present invention may also be used toform underground storage tanks. It is easier to make a box out of thedrainage modules of the present invention than with existing drainagemodules of the type which do not engage in both end to end relation andnormally to each other. The modules can be interlocked to form a boxhaving no ends. Custom made ends and centre sections, may then be fittedto stabilise and give rigidity to the box and the box may then becovered with a geotextile to form an underground storage tank.

[0048] A pattern of small holes, or other markings may be provided onthe upper member 12 to indicate which face of the drainage member shouldface upwards.

[0049] The size and shape of the module may be varied from thatdescribed. The module may be any shape (e.g. hexagonal). Typically, themodules will be either square or have one side which is a multiple (e.g.2 times) the length of the other.

[0050] Although the above description refers to a drainage module, thatis only one use of the structural module of the present invention andother uses, such as those discussed on page 5 of the specification, arepossible.

The claims defining the invention are as follows:
 1. A structural modulecomprising: a first and a second substantially parallel generally planarmember retained in a fixed spaced relationship from each other by aplurality of spacers extending between the first and second planarmembers, the module having side edges extending between perimeters ofthe first and second planar members and wherein each planar memberdefines an ordered array of apertures; male interlocking means which areintegral with the module projecting from at least a first one of theside edges; female interlocking means defined in at least a second ofthe side edges adapted to receive a male interlocking means so that twomodules can be secured together in side edge to side edge relation;characterised in that the size and configuration of the male lockingmeans relative to the size and configuration of the apertures, is suchthat a first module may also be inter-engaged with a second module, withthe first module oriented generally normally to the second module with aside edge of the first module abutting a planar member of the secondmodule and with each male locking means defined along said side edge ofthe first member extending into one of the apertures defined in one ofthe planar members in a close or interference type fit with theaperture.
 2. A structural module as claimed in claim 1 wherein thefemale locking means comprise elongate slots defined in side edges ofthe module.
 3. A structural module as claimed in claim 2 wherein theslots have an open end and a closed end.
 4. A structural module asclaimed in claim 1, 2 or 3 wherein the male locking means comprise twoarms which are generally L shaped in planar cross section whose distalends locate behind the side edges adjacent the elongate slot when twomodules are interlocked in side edge to side edge relation.
 5. Astructural module as claimed in any one of the preceding claims whereinthe apertures are generally circular and the perimeter of the malelocking means is also generally circular.
 6. A structural module asclaimed in any one of the preceding claims wherein the area of theapertures comprise at least 50% of the surface area of the first andsecond planar members.
 7. A structural module as claimed in any one ofthe preceding claims wherein the apertures in the planar members arearranged substantially regularly and uniformly.
 8. A structural moduleas claimed in any one of the preceding claims wherein the male lockingmeans are equidistantly spaced along a first two adjacent sides of themodule.
 9. A structural module as claimed in claim 8 wherein thearrangement of male locking means along each adjacent side isasymmetric.
 10. A structural module as claimed in claim 9 wherein thefemale locking means are equidistantly and asymmetrically spaced alongthe other two sides of the module.
 11. A structural module as claimed inally preceding claim wherein a series of gaps are also disposed betweeneach pair of female locking means, the gaps being wider than the malemembers.
 12. The use of a module to as claimed in any preceding claim tomake drainage piping or underground tanks by assembling and interlockingthe modules into boxes or pipes and covering them with a geotextile orlike material.
 13. A tank for use underground comprising modules asclaimed in any one of claims 1 to 11 assembled into a box structure andcovered with a geotextile.
 14. Drainage piping for use undergroundcomprising modules as claimed in any one of claims 1 to 11 assembledinto an elongate open ended box structure and covered with a geotextile.